Universal joints for coupling rotary shafts at an angle and transmitting torque therebetween are well known and of many different varieties. One such variety is known as a cone style universal joint. An example of such a universal joint is described in U.K. patent application GB 2,107,824 A.
A typical cone style universal joint has two identical yokes and a cone bearing is pinned on the inside surface of each arm of the yokes. Each cone bearing has a conical surface which bears against the conical surfaces of two adjacent cone bearings. Each cone bearing also has a spherical surface at its inside end which is in sliding contact with a ball. Thereby, as torque is transmitted from one yoke to the other, the point of intersection of the shaft axes of rotation remains at the center of the ball.
One problem with universal joints and specifically with cone style universal joints is lubrication. During rotation, parts of the universal joint slide relative to one another, which can result in excessive wear without proper lubrication. Aggravating the problem is that as the joint is rotated, significant centrifugal forces are generated which tend to evacuate all lubricant from the joint.